People realize a romance manga can keep going after a couple confesses and starts going out, right?
No because there is a victory condition that was meet,
if it continues then all we are going to get is melodrama as there is no other way to add tension back without putting the relationship in danger.
Also plenty of series have done so, I"s for example were after they "confess" the whole thing takes a nosedive in a attempt to "break then up", Kare Karo were for volumes after its about the supporting cast having their pairings (and that worked quite well, I enjoyed those side stories) added with more drama and after that is solved, it kinda ends ... and speaking of Jitsu wa Watashi wa not only it ends right after everyone exposes their secret (that was the title of the series and the original focus) but also after they paired up they also had to bring up melodrama to add stress to their relationship.
Of course it can "keep going" but its over, at that point we either get melodrama or nothing ... stories have a theme and a structure and you cannot just shift it to something else, the core of this story is Tomo wants to date Jun, thats solved and thats solved ... ITS THE END OF THE STORY.